OpenStax Glossary Notes — Part 1: A terms

A terms

• 454 sequencing (pyrosequencing): a next generation sequencing technique in which fragmented DNA has DNA adapters attached, is amplified by PCR, is attached to a bead, and then placed into a well with sequencing reagents, and the flash of light produced by the release of pyrophosphate on addition of a nucleotide is monitored

• Aα-helix: secondary structure consisting of a helix stabilized by hydrogen bonds between nearby amino acid residues in a polypeptide

• A (aminoacyl) site: functional site of an intact ribosome that binds incoming charged aminoacyl tRNAs

• A-B exotoxin: class of exotoxin that contains A subunits, which enter the cell and disrupt cellular activities, and B subunits, which bind to host cell receptors

• ABO blood group system: set of glycoprotein antigens found on the surface of red blood cells; the presence or absence of specific carbohydrates determining blood type

• absorbance: when a molecule captures energy from a photon and vibrates or stretches, using the energy

• Acanthamoeba keratitis: a condition characterized by damage to the cornea and possible blindness caused by parasitic infection of the protozoan Acanthamoeba

• acellular: not made of cells

• acid-fast stain: a stain that differentiates cells that have waxy mycolic acids in their gram-positive cell walls

• acidic dye: a chromophore with a negative charge that attaches to positively charged structures

• acidophile: organism that grows optimally at a pH near 3.0

• acne: a skin disease in which hair follicles or pores become clogged, leading to the formation of comedones and infected lesions

• acquired immunodeficiency syndrome (AIDS): disease caused by HIV, characterized by opportunistic infections and rare cancers

• actin: a protein that polymerizes to form microfilaments

• activation energy: energy needed to form or break chemical bonds and convert a reactant or reactants to a product or products

• activator protein: that increases the transcription of a gene in response to an external stimulus

• active carrier: an infected individual who can transmit the pathogen to others regardless of whether symptoms are currently present

• active immunity: stimulation of one’s own adaptive immune responses

• active site: location within an enzyme where substrate(s) bind

• acute disease: disease of a relatively short duration that develops and progresses in a predictable pattern

• acute glomerulonephritis: inflammation of the glomeruli of the kidney, probably resulting from deposition of immune complexes and an autoimmune response caused by self-antigen mimicry by a pathogen

• acute necrotizing ulcerative gingivitis: a severe form of gingivitis, also called trench mouth

• acute otitis media: inflammatory disease of the middle ear resulting from a microbial infection

• acute rheumatic fever: sequela of streptococcal pharyngitis; comorbidities include arthritis and carditis

• acute-phase proteins: antimicrobial molecules produced by liver cells in response to pathogen-induced stimulation

• Alphaproteobacteria: class of Proteobacteria that are all oligotrophs

• alphaproteobacteria: Alphaproteobacteria (as above) — class of Proteobacteria that are all oligotrophs

• amantadine: antiviral drug that targets the influenza virus by preventing viral escape from endosomes upon host cell uptake, thus preventing viral RNA release and subsequent viral replication

• amensalism: type of symbiosis in which one population harms the other but remains unaffected itself

• Ames test: method that uses auxotrophic bacteria to detect mutations resulting from exposure to potentially mutagenic chemical compounds

• amino acid: a molecule consisting of a hydrogen atom, a carboxyl group, and an amine group bonded to the same carbon. The group bonded to the carbon varies and is represented by an R in the structural formula

• aminoacyl-tRNA synthetase: enzyme that binds to a tRNA molecule and catalyzes the addition of the correct amino acid to the tRNA

• aminoglycosides: protein synthesis inhibitors that bind to the 30S subunit and interfere with the ribosome’s proofreading ability, leading to the generation of faulty proteins that insert into and disrupt the bacterial cytoplasmic membrane

• amoebiasis: intestinal infection caused by Entamoeba histolytica

• amoebic dysentery: severe form of intestinal infection caused by Entamoeba histolytica, characterized by severe diarrhea with blood and mucus

• amphipathic: a molecule containing both polar and nonpolar parts

• amphitrichous: having two flagella or tufts of multiple flagella, with one flagellum or tuft located at each end of the bacterial cell

• amphotericin B: antifungal drug of the polyene class that is used to treat several systemic fungal infections

• amplitude: the height of a wave

• anabolism: chemical reactions that convert simpler molecules into more complex ones

• anaerobe chamber: closed compartment used to handle and grow obligate anaerobic cultures

• anaerobe jar: container devoid of oxygen used to grow obligate anaerobes

• anaerobic respiration: use of a nonoxygen inorganic molecule, like CO2, nitrate, nitrite, oxidized iron, or sulfate, as the final electron acceptor at the end of the electron transport system

• analytical epidemiology: study of disease outbreaks to establish associations between an agent and a disease state through observational studies

• anaphylactic shock: another term for anaphylaxis

• anaphylaxis: systemic and potentially lifethreatening type I hypersensitivity reaction

• anergy: peripheral tolerance mechanism that prevents self-reactive T cells from being activated by self-antigens through lack of co-stimulation

• albendazole: antihelminthic drug of the benzimidazole class that binds to helminthic β-tubulin, preventing microtubule formation

• algae (singular: alga): any of various unicellular and multicellular photosynthetic eukaryotic organisms; distinguished from plants by their lack of vascular tissues and organs

• alkaliphile: organism that grows optimally at pH above 9.0

• alkylating agent: type of strong disinfecting chemical that acts by replacing a hydrogen atom within a molecule with an alkyl group, thereby inactivating enzymes and nucleic acids

• allergen: antigen capable of inducing type I hypersensitivity reaction

• allergy: hypersensitivity response to an allergen

• allograft: transplanted tissue from an individual of the same species that is genetically different from the recipient

• allosteric activator: molecule that binds to an enzyme’s allosteric site, increasing the affinity of the enzyme’s active site for the substrate(s)

• allosteric site: location within an enzyme, other than the active site, to which molecules can bind, regulating enzyme activity

• allylamines: class of antifungal drugs that inhibit ergosterol biosynthesis at an early point in the pathway

• Alphaproteobacteria (repeat): class of Proteobacteria that are all oligotrophs (see above)

• Amantadine (repeat): antiviral drug (see above)

• Amensalism (repeat): (see above)

• Ames test (repeat): (see above)

• Amino acid (repeat): (see above)

• Aminoacyl-tRNA synthetase (repeat): (see above)

• Aminoglycosides (repeat): (see above)

• Amoebiasis (repeat): (see above)

• Amphipathic (repeat): (see above)

• Amphitrichous (repeat): (see above)

• Amphotericin B (repeat): (see above)

• Amplitude (repeat): (see above)

• Anabolism (repeat): (see above)

• Anaerobe chamber (repeat): (see above)

• Anaerobe jar (repeat): (see above)

• Anaerobic respiration (repeat): (see above)

• Analytical epidemiology (repeat): (see above)

• Anaphylactic shock (repeat): (see above)

• Anaphylaxis (repeat): (see above)

• An age? (terminology repeated in glossary; see above)

• Albendazole (repeat): (see above)

• Algae (repeat): (see above)

• Alkali? (covered as alkaliphile)

Note: This Part 1 covers the A terms from the transcription. If you’d like, I can continue with Part 2 covering B terms and beyond, in subsequent messages or in additional chunks. Let me know how you’d like to pace the notes (e.g., per alphabet, by topic clusters, or by lecture segments).